PBB-PA has been known for some time, and is a valuable flame-retardant material, useful in a number of synthetic resins. PBB-PA is prepared by the polymerization of pentabromobenzylester acrylate (PBB-MA), e.g., by the process described in DE 25 27 802. The PBB-PA polymeric flame-retardant material is incorporated into the synthetic resin to which it is desired to impart flame-retardant properties, by techniques known in the art.
The use of this valuable flame-retardant material, however, has been somewhat limited so far because of its limited thermal stability. Thermal stability, as will be known to the skilled person, is an important property both in the lifetime of the synthetic resin which embodies the flame-retardant material, as well as during its preparation. The use of many flame-retardant materials is limited, because the compounding temperatures required in order to incorporate it into a given resin are too high, and the flame-retardant material is not thermally stable enough to permit its compounding at such temperatures. Consequently, flame-retardant materials which would be efficient in certain resins are not used, because it is impossible to effect the compounding operation, without adversely affecting the flame-retardant material.